The present invention relates to a program rating (audience rating) measuring system and, more particularly, to a system for detecting the recording data of a video tape recorder, which system is adapted to detect data concerning the time and channel when and where a program being played back by the video tape recorder was recorded.
In recent years, the use of video tape recorders has become widespread, and the importance of sampling data on the use of the video tape recorder has been increasing for accurately surveying TV program ratings.
Thus, in Japanese Patent Applications Nos. 58-71221 (1983/71221), 58-107896 (1983/107896), 58-107897 (1983/107897) (corresponding to U.S. Pat. No. 4,574,304) and 59-143052 (1984/143052) (corresponding to U.S. Pat. No. 4,622,583), we have already proposed methods and apparatus for detecting the operating states of the video tape recorder so that the audience situations may be grasped in case the video tape recorder is used in combination with a television set.
However, what can be surveyed by that prior art has been limited to date concerning how the video tape recorder is used in each instance, i.e., the data indicating the states of stop, playback, recording and monitoring (that a program selected by the tuner of the video tape recorder is being observed through a TV set) as well as the channel data indicating which channel is being recorded. The prior art has failed to detect what program is being played back for the actual observation, i.e., the time and channel when and where the program being viewed was recorded. Therefore, the prior art cannot provide a sufficient variety of data and is deficient as it cannot provide sufficient research concerning the program ratings of families using TV sets and video tape recorders together.